TPMS System Data

[romoman]

I thought folks might like to see some data from a TPMS system. It provides a really great insight into how tires heat up and "come in." It can also teach you a lot about when to start making changes!

First thing is it's easy to integrate alarms so you would know if you had a flat or a tire going down. With all the new dashes, it also lets you display tire pressures on the dash.



This shot shows a great way to determine tire pressures. A simple XY plot of tire pressure versus lateral G (or grip factor, long G, etc) will show what pressure allowed the tire to make the most grip. This data is from a tin top, as seen in the higher pressures, but you can get the idea.



This is a great shot of how long it takes tires to warm up and how much pressure gain you really get. This is important to see so you know when the tires "come in" and you can also work with driver feedback to see when the driver feels the tires are better versus what tire pressures really were.



This is a great shot of being able to see how tires cool down during slower laps. Depending on the car, track, ambient conditions, you can see between 1-5 psi drop in pressures during a yellow.



Easy to use channel report showing the tire pressures throughout a run.




This system also has internal tire air temp, which is great for using the Ideal Gas Law (thing Deflategate with Tom Brady). If you know the normal hot operating temp, desired pressure, and the current temp, you can predict the starting inflation pretty accurately.

The system itself connects to your data system with a CAN connection, power, and ground. It's a small module that mounts in the car and then uses valve stem cap sensors. They have been used in almost every form of racing, seeing speeds over 200 mph and temps over 600F. If anyone is interested in them, shoot me a PM or an email at matt@jraplastics.com. Systems are $1,800 each and are essentially plug and play.

[Will Velkoff]

Very interesting and useful data. Nice!

[mikey]

Interesting. I wonder if rim mounted sensors like OEMs use now could be used instead along with a wireless receiver and CAN output box. I’m quite certain this can be done for much less $$!

I’m going to investigate.. would definitely like to have this data.

[romoman]

Interesting. I wonder if rim mounted sensors like OEMs use now could be used instead along with a wireless receiver and CAN output box. I’m quite certain this can be done for much less $$!

I’m going to investigate.. would definitely like to have this data.

Pricing for that sort of system from a motorsport supplier is $3,500+. I've heard the McLaren TPMS system is north of $25k. Many of those style systems have problems too. One of them stops transmitting when the sensor reaches 247F, another has power problems, and the other two have some issues as well. No system is perfect.

There are budget trailer systems available, but they are around 1 sample per minute at best, have pressure sensors that are designed for roughly 100 psi (won't be accurate at motorsport levels), and are plagued by leaks. The larger issue on many of them is that they will only send data to a phone or display.

This system is guaranteed, doesn't leak, and has upgraded sensors that will work in the proper pressure range. We've even calibrated them for use on karts at single digit pressures.

[mikey]

Got it, and I’m sure it’s a nice system, but I’m thinking more along the lines of OEM solutions for say, a Corvette. Data ends up in the OBD2 stream so I’m betting with some research I can find some re-use code and hardware that could be adapted. The sampling rate may or may not be sensor dependent, if not it could be easily changed. Accuracy of sensors I’m sure can drive cost as well, but within 1lb would work for the amateur crowd in most cases. $1800 or more for tire sensors isn’t a tenable discussion to a bunch of amateurs who don’t even want to spend half of that on tires themselves!

Are you advertising this system? Do you build it or sell it?

[romoman]

Got it, and I’m sure it’s a nice system, but I’m thinking more along the lines of OEM solutions for say, a Corvette. Data ends up in the OBD2 stream so I’m betting with some research I can find some re-use code and hardware that could be adapted. The sampling rate may or may not be sensor dependent, if not it could be easily changed. Accuracy of sensors I’m sure can drive cost as well, but within 1lb would work for the amateur crowd in most cases. $1800 or more for tire sensors isn’t a tenable discussion to a bunch of amateurs who don’t even want to spend half of that on tires themselves!

Are you advertising this system? Do you build it or sell it?

I don't think the OBDII transmission includes TPMS on any car. The CAN connection may, but it's normally on the chassis bus and not the engine bus. I haven't seen or heard of anyone successfully tapping into it, though I'm sure it could be done.

I sell these systems. For this post, I was sharing how the data works and offering them for sale. This is the same type of data that is used in Indycar, F1, NASCAR testing, IMSA, etc. I thought people would like to see how it works and what can be done with it.

[BeerBudgetRacing]

Got it, and I’m sure it’s a nice system, but I’m thinking more along the lines of OEM solutions for say, a Corvette. Data ends up in the OBD2 stream so I’m betting with some research I can find some re-use code and hardware that could be adapted. The sampling rate may or may not be sensor dependent, if not it could be easily changed. Accuracy of sensors I’m sure can drive cost as well, but within 1lb would work for the amateur crowd in most cases. $1800 or more for tire sensors isn’t a tenable discussion to a bunch of amateurs who don’t even want to spend half of that on tires themselves!

Are you advertising this system? Do you build it or sell it?

If I understand this, the stem caps are the sensors and transmit the data. Slick.

Have you looked at road car TPMS sensors? They get installed INSIDE the wheel, are large and heavy.
You'll need a set for each set of wheels. You'll need to go though the reset process each time you change wheel sets.
They probably aren't accurate below 20psi.

You're right, $1800 is steep for amateurs, but I suspect adapting a road set is going to cost $1000 and be a lot of work to use.
IMO, if it's difficult to use you won't use it.

[Lotus7]

Will be curious to try the following next season:

My '4-screw-on-sensors' trailer TPS system was $250, and has a 2"x3" stand-alone display that I can velcro to the dash in a practice session.
Drive laps, watching display frequently, then compare last readings with pit lane gauge readings. Sampling rates unknown, and no temperature data, but might get usable "how many laps until tires are up to pressure?" info essentially for free.

[romoman]

Will be curious to try the following next season:

My '4-screw-on-sensors' trailer TPS system was $250, and has a 2"x3" stand-alone display that I can velcro to the dash in a practice session.
Drive laps, watching display frequently, then compare last readings with pit lane gauge readings. Sampling rates unknown, and no temperature data, but might get usable "how many laps until tires are up to pressure?" info essentially for free.

Tire, setup, and track dependent, but I'll save you the work and say 2-3 laps for most common tires. Their are some brands/styles that are different. Some drivers can do it a bit quicker, some a bit slower, some shock setup faster, some slower.

A better question is when you "feel" like the tires are in or up to pressure versus when the actually are. That is usually a pretty big variance. The other is what pressure actually provides the best grip (measure how you want) versus what people think/institutional knowledge/feelings.

[DanW]

https://www.bestbuy.com/site/papago-...?skuId=5925205

[phantomjock]

Will be curious to try the following next season:

My '4-screw-on-sensors' trailer TPS system was $250, and has a 2"x3" stand-alone display that I can velcro to the dash in a practice session.
Drive laps, watching display frequently, then compare last readings with pit lane gauge readings. Sampling rates unknown, and no temperature data, but might get usable "how many laps until tires are up to pressure?" info essentially for free.

I just installed a similar system I got from a firm based in India. It is Bluetooth enabled, and links to the phone (mounted in the cockpit. Gives pressure updates and temp (at the point of the sensor). If interested it is called SENSAIRY. May be a low cost useful approach. I got it for my crew to read post lap pressure data rather than pull the rear body. Faster read--closer to "truth".

As Bluetooth I suppose through a device it could be added to a DA setup. Appears to be within about 1 psi -- garage testing only. My pyro is toast, so cant say on that.

Not terribly expensive - under $150, free download, fast shipping too. Not associated - just liking so far, will know more when we ops test.

Cheers - Jim

[BeerBudgetRacing]

Tons on Amazon. If you try one take note of the low end of the range. Post results here:

This one is pressure and temp: $72
https://www.amazon.com/Universal-Wir...itoring+system

But for racing these specs are probably not best:
Pressure Accuracy: ±1.5Psi
Temperature Accuracy: ±3 C

It's looking more and more like we'll all be carrying a bluetooth enabled tablet in our cars for some thing or another. Good thing they are cheap.

[DanW]

Tons on Amazon. If you try one take note of the low end of the range. Post results here:

This one is pressure and temp: $72
https://www.amazon.com/Universal-Wir...itoring+system

But for racing these specs are probably not best:
Pressure Accuracy: ±1.5Psi
Temperature Accuracy: ±3 C

It's looking more and more like we'll all be carrying a bluetooth enabled tablet in our cars for some thing or another. Good thing they are cheap.

Something to monitor on your phone or tablet while you're in the car....

https://www.drivermonitor.app/?fbcli...rLskp5pUFI_LzA

[BeerBudgetRacing]

Something to monitor on your phone or tablet while you're in the car....

https://www.drivermonitor.app/?fbcli...rLskp5pUFI_LzA

Apple stuff is too expensive!

How about an Android tab for $50?
https://www.amazon.com/NeuTab-Androi...android+tablet

[TimW]

I don't think the OBDII transmission includes TPMS on any car. The CAN connection may, but it's normally on the chassis bus and not the engine bus. I haven't seen or heard of anyone successfully tapping into it, though I'm sure it could be done.

It’s been done.
https://www.mazdamotorsports.com/201...ng-information

It is queryable from known PIDs if you know where to look, for most cars that came with tpms from oem.

You’re correct it doesn’t come from the pcm but it usually does come from another ecu on the same bus as that ecu consumes pcm data, at least on the cars I investigated.

[phantomjock]

Wifi Lapper - now upgraded to "SpeedFreq" is an app that runs on phone/tablet. Its a low-cost data logger, lap timer, and telemetry (TM) app. It can use a Bluetooth GPS for greater accuracy, and for nerds, heart rate too.

https://sites.google.com/site/wifila...e-to-speedfreq

Its most notable feature is it can TM over WIFI to your crew through an inexpensive WIFI router mounted onboard. Outputs and session summary are all similar to the higher priced options, but it is limited to the gyro/axis accuracy of your phone/tablet. I've played around a bit with it for a few years, but haven't used the TM, yet.

the app: https://play.google.com/store/apps/d...ahon.speedfreq

It would be interesting to see if they can add in the TPMS to another channel too.

There is a limit to how much data and detail you'd want too try and process during a session, but the pitside crew could. (They have the app, PitSide just for that. The router downloads to the pit when you are in range.) It has the choice of using a mobile phone or WIFI based, which affords some security.

Video example of session/lap on the 'Tube: https://www.youtube.com/watch?v=L7dtS2aaYrU

TM of live-ontrack video I think is still a "Holy Grail" for privateers.

Standard disclaimer; uninvolved, just interested user/beta tester.

Cheers - Jim

[romoman]

It’s been done.
https://www.mazdamotorsports.com/201...ng-information

It is queryable from known PIDs if you know where to look, for most cars that came with tpms from oem.

You’re correct it doesn’t come from the pcm but it usually does come from another ecu on the same bus as that ecu consumes pcm data, at least on the cars I investigated.

I saw that article - it came out after my posts. Cool they were able to get it. I haven't seen anyone else get this info on any other model. I'm sure it's in there, but no one has invested the time to get it. Cool stuff for sure.

[Garey Guzman]

This is definitely an item I would like data on, just wish I could afford the $1800 for this system. Tire pressure and temp is, I think, critical to understanding how the car is working.

Until I can save up for this, I will try the cheaper versions described to see if they work.

[problemchild]

This would be a fascinating tool to have.
However, from what I see in club racing and semi-pro racing, it would be a complete waste. Managing tire pressures is the easiest task that there is, yet an overwhelming majority are not putting any effort into it. Every session needs a hot in-lap with pressures taken promptly. If you start recording TP, before, after, and during each session, where possible, combining appropriate bleeding down, while noting ambient and track temps, then you will be able to race on optimum TP, within a reasonable window. Even a crewless driver, or with disinterested spouse, can record pressures after a session. There is a reason that winning cars stop on their in-lap, even after winning the final race of an event, to get TP.
if you are reading this thread, and pining over such a system that you cannot afford, it is time to evaluate your current TP monitoring process, and update it.

[Garey Guzman]

This would be a fascinating tool to have.
However, from what I see in club racing and semi-pro racing, it would be a complete waste. Managing tire pressures is the easiest task that there is, yet an overwhelming majority are not putting any effort into it. Every session needs a hot in-lap with pressures taken promptly. If you start recording TP, before, after, and during each session, where possible, combining appropriate bleeding down, while noting ambient and track temps, then you will be able to race on optimum TP, within a reasonable window. Even a crewless driver, or with disinterested spouse, can record pressures after a session. There is a reason that winning cars stop on their in-lap, even after winning the final race of an event, to get TP.
if you are reading this thread, and pining over such a system that you cannot afford, it is time to evaluate your current TP monitoring process, and update it.

All very true. As a crewless driver, it is very difficult to get TP after a session and impossible to get in the middle of a session. Being able to look at data to understand what's going on would be invaluable to understanding that cool down/bleed down process and therefore, where to start the pressure for optimum performance.
That said, it probably wouldn't be a tool necessary after understanding the tire heating/cooling processes. That's why I bought a cheapo system off Amazon. I'll see if it works and if not, not much of a loss. (thank you Black Friday)

[phantomjock]

This is a screenshot of the Sensairy app:

It is not from my vehicle but representative.

We had hoped to trial it at Sebring this weekend, but other issues kept us from making the trip.

I got it to make it easier for my wife/partner//crew to get the in-lap pressures without climbing over the inner pit wall. A couple of things to note about it:

1. It has a minimum pressure limit of 20 psi. (that fits our range just fine) The temp measurements are within 5C, and only at the valve stem location, not contact patch.

2. It is mounted inside the tire. If the wheel/rim is narrow at the bead location, it may give your shop fits getting it in the space. My guy did just fine but had to fiddle with it.

3. When it is installed you pair it with the device you want to use. The shop paired to their i-phone, but I had the firm - "re-pair" to my device.

4. Its accuracy is advertised at +/- 1 psi (close is better than not taking the temp at all)

5. A set of 4 was about 120 bucks, and 1/2 of that was shipping. But it came from India in 3 days! Shipping was built into the cost.

6. I've asked if they can adjust the "history" tab of the app, to finer granulation than 1 day increments. We'll see what they can come up with.

Just wanted to provide better input for those seeking options.

Cheers - Jim